HealthlineNews

Cannabis Fails to Slow Progression of MS, Study Finds

Written by Jeri Burtchell
| Published on July 31, 2013

While the CUPID study failed to prove that cannabis slows multiple sclerosis progression, scientists are optimistic for the future of MS research.

In the first large-scale, multi-center study
of its kind, researchers in the UK hoped to prove that cannabis could
slow the progression of multiple sclerosis (MS). But their newly
published results are not promising.

Dubbed CUPID (Cannabinoid
Use in Progressive Inflammatory Brain Disease), the trial involved
nearly 500 people with progressive MS. In progressive MS, there
are no distinct relapses or remissions. Instead, patients experience a
slow, steady decline with an accumulation of disability. It took eight years to complete the placebo-controlled study, which mapped patients’ disease progression over three years.

THC Fails to Slow Multiple Sclerosis

In
the CUPID study, two-thirds of patients received dronabinol, a
synthetic version of THC (the active chemical in cannabis), while the
rest took a placebo. Patients took the medication daily for three years
and their disability scores were mapped using the Expanded Disability
Status Scale (EDSS). They also completed questionnaires rating the
impact of MS on their daily lives.

CUPID failed to prove
that dronabinol could slow MS progression, although some patients at the
lower end of the disability scale did appear to benefit.

“The
effect we found in people with less disability is very interesting, and
needs further exploration. There are many possible explanations,” said John
Zajicek, chief investigator of the CUPID study and a professor of
clinical neuroscience at Plymouth University Peninsula Schools of
Medicine and Dentistry. “The first is that
this is a chance finding that won’t be repeatable,” he said. But he
feels the most likely explanation is that “...these people are
progressing the fastest, so we have most chance of seeing an effect.”

Taking
the relaxing effects of cannabis into account, Zajicek told Healthline,
“[It] may be that as people have more difficulty with walking, the
anti-stiffness effect of cannabinoids means that we are removing the
stiffness needed to remain walking, so we get a 'masking' of potential
protective effects.”

Unpleasant side effects of dronabinol
could also have played a role in the trial outcome. As Zajicek pointed
out, “Side effects meant that people stopped medication more frequently
in the active treatment arm.”

Sativex is currently
the only licensed cannabis medication on the market, and some MS
patients use it to treat symptoms like muscle cramping and pain.

Measuring MS Progression

CUPID researchers were surprised to find that, overall, MS progressed at a slower rate than they'd expected. This suggests that a longer trial might yield a more favorable result.

The problem is, according to Zajicek,
that “MS studies in progressive disease are incredibly difficult to do.
Three years is about as long as it is possible to keep people in
trials.”

In the CUPID trial, patients didn't deteriorate as fast
as expected, so if researchers hope to see any potential effect of
treatment, Zajicek said, “We need to make sure that in future we try and recruit people who have most chance of progressing.”

Testing New Research Methods

CUPID also aimed to improve the way MS clinical trials are conducted.

Zajicek said trials of progressive MS have always used the Expanded Disability Status Scale,
“which is a very old measurement scale, with many shortcomings. In
CUPID, we used patient-reported outcome as a co-primary measure,
alongside the EDSS.”

And while traditional trials
compare the study's entire treatment group to the entire placebo group, Zajicek
said, “This doesn’t take account of the vast amount of data every trial
actually generates, and doesn’t allow us to estimate the size of benefit
for any single person. By using newer methods, we should be able to
spot sub-groups of people who may be most likely to benefit. Statistics
has moved on considerably, but most clinical trials (in all diseases)
don’t make the most of these advances.”

Looking Ahead to Future Studies

Zajicek
emphasized, “There is a desperate need for more studies in progressive
MS.” He added that the International Progressive MS Consortium is
dedicated to organizing such research. “We need to extract as much
information from the CUPID study as possible before we embark on more
trials.”

An upcoming study called MS-SMART will
use MRI scans to screen for a range of drugs that might help slow
progressive MS. However, considering the financial and temporal burden
of large-scale trials, Zajicek is hesitant to sign on for
another round. “As [CUPID] took eight years, an incredible amount of
effort, and overcoming major problems with funding, I’m not sure I’m the
person to take this on,” he said.

And people with MS can have an impact. Let organizations like the National Multiple Sclerosis Society (NMSS)
or the Multiple Sclerosis Association of America (MSAA) know there is a
need. “If people affected by MS want me to take this forward,” said
Zajicek, “and there are sufficient funds, then I might be persuaded.”

“We’re
also trying to do studies in other areas of MS,” he added, “such as
comparing some of the latest treatments head-to-head, and testing the
value of adding vitamin D to see if this influences the disease course.
There’s a lot that needs to be done.”

Healthline’s mission is to make the people of the world healthier through the power of information. We do this by creating quality health information that is authoritative, approachable, and actionable.

Join more than 30 million monthly visitors like you and let Healthline be your guide to better health.